Sonic boom: From bang to puff.

For almost 40 years commercial supersonic flight over land has been prohibited because of the negative impact of sonic booms. During that time, technology advances have raised the possibility of a muted sonic boom—a sonic “puff”—that could be acceptable over populated areas. This paper reviews the physics of sonic boom generation and propagation, and why booms from conventional aircraft are usually N-waves with unacceptably large shock waves. The low-boom shaping technology that can minimize shocks, thus reducing sonic boom loudness to acceptable levels, is presented. The success of the DARPA/NASA Shaped Sonic Boom Demonstrator in validating shaping theory is discussed. Concepts for attaining practical aircraft configurations, versus ideal optimal shapes, are described.